I hear this one a lot. People who use Microsoft Office most of the time feel no need to change. It works just fine for them. It's the standard according to them. So on and so forth.

I don't know if Office supports writing to ODF, but if it does then maybe the best solution is to convince people to save documents in that format. Don't try to convince them that OpenOffice is the greatest or that some other solution is the best. Let them use what they want and save in a more universal format. Then someday in the future maybe they will be ok with switching when they see that they docs they have will work just fine in many other office formats.

(Also. Lets not forget Excel. Most people I know that are die hard Office users are that way because of Excel and not Word.)